The use of air conditioners during the summer months requires large quantities of energy primarily during the daytime hours when other forms of energy consumption are also high. Peaking generators are required to increase electricity generating capacity so that power loads are met. However, energy consumption decreases dramatically at night, and the peaking generators are not needed. Thus, the expensive peaking generators are run only half the time, decreasing the efficiency of the power facility. To alleviate this problem, thermal energy storage systems, which can utilize off peak, night-time electricity have been proposed.
Thermal energy storage systems contain a cooling medium, which is frozen during the off peak, evening hours. During the daytime, heat from the surrounding area is used to melt the frozen cooling medium. The removal of heat to drive the decomposition causes the surrounding area to become cooler.
Gas or liquid clathrates made from refrigerants and water have been suggested as cooling media suitable for thermal energy storage systems. For example, U.S. Pat. No. 4,540,501 discloses using as the guest molecule a refrigerant chosen from brominated, chlorinated and fluorinated hydrocarbons including CCl.sub.2 F.sub.2, CCl.sub.3 F, CBr.sub.2 F.sub.2, CH.sub.2 ClF and CH.sub.3 CClF.sub.2.
However, many of the guest molecules presently being used are CFCs such as trichlorofluoromethane (R-11). The use of these compounds is becoming disfavored because of the possible detrimental effect to the ozone layer. Hydrofluorocarbons are believed to pose no threat to the ozone layer, and are thus the preferred guest molecules.